static int w1_ds2505_read_page()

in slaves/w1_ds250x.c [84:138]

• 44 lines of code
• 7 McCabe index (conditional complexity)

static int w1_ds2505_read_page(struct w1_slave *sl, int pageno)
{
	struct w1_eprom_data *data = sl->family_data;
	int redir_retries = 16;
	int pgoff, epoff;
	int ret = -EIO;
	u8 buf[6];
	u8 redir;
	u16 crc;

	if (test_bit(pageno, data->page_present))
		return 0; /* page already present */

	epoff = pgoff = pageno * W1_PAGE_SIZE;
	mutex_lock(&sl->master->bus_mutex);

retry:
	if (w1_reset_select_slave(sl))
		goto err;

	buf[0] = W1_EXT_READ_MEMORY;
	buf[1] = pgoff & 0xff;
	buf[2] = pgoff >> 8;
	w1_write_block(sl->master, buf, 3);
	w1_read_block(sl->master, buf + 3, 3); /* redir, crc16 */
	redir = buf[3];
	crc = crc16(CRC16_INIT, buf, 6);

	if (crc != CRC16_VALID)
		goto err;


	if (redir != 0xff) {
		redir_retries--;
		if (redir_retries < 0)
			goto err;

		pgoff = (redir ^ 0xff) * W1_PAGE_SIZE;
		goto retry;
	}

	w1_read_block(sl->master, &data->eprom[epoff], W1_PAGE_SIZE);
	w1_read_block(sl->master, buf, 2); /* crc16 */
	crc = crc16(CRC16_INIT, &data->eprom[epoff], W1_PAGE_SIZE);
	crc = crc16(crc, buf, 2);

	if (crc != CRC16_VALID)
		goto err;

	set_bit(pageno, data->page_present);
	ret = 0;
err:
	mutex_unlock(&sl->master->bus_mutex);
	return ret;
}